Evaluation of ArcCHECK SNC Machine QA tool for Modern Linear Accelerator
Purpose: ArcCHECK SNC Machine QA tool is used to test geometric and delivery aspects of linear accelerator.
Methods: In this study we evaluated the performance of this tool. For each item analyzed by the tool, wherever possible, tests across the same time period using portal dosimetry were also evaluated. Machine QA feature allows user to perform quality assurance tests using ArcCHECK phantom. Following tests can be performed 1) Gantry Speed, Rotation and Angle 2) MLC/Collimator 3) Beam Profile Flatness and Symmetry. Data was collected on true BEAM STx for a year. All plans were created for 6 and 10 MV beams as per the SNC patient user manual in Eclipse v.13.
Results: The Gantry speed was 3.9 deg/sec with speed maximum deviation around 0.3 deg/sec. The Gantry Isocenter for arc delivery was 0.9 mm and static delivery was 0.4 mm which was well consistent with MPC (0.4 mm). The average maximum percent positive and negative diff was found to be 1.9%, -0.25% and average maximum distance positive and negative diff was 0.4 mm, -0.3 mm for MLC/Collimator QA. The average gamma error at 1% 1 mm criteria was 1.4% using portal Dosimetry for 6 MV. The Flatness for Arc delivery was 1.8% and Symmetry for Y was 0.8% and X was 1.8%.
Conclusion: ArcCHECK SNC Machine QA tool is useful for quality assurance of modern linear accelerators as it tests both geometric and delivery aspects. This test can be incorporated in the regular quality assurance protocol for VMAT delivery.
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